Arnold & Son HM Double Hemisphere Perpetual Moon (Royal Collection)

Featuring a translucent blue lacquered guilloché dial, the new HM Double Hemisphere Perpetual Moon from Arnold & Son’s Royal Collection incorporates two mega moon-phase indications. For the first time, the HM Double Hemisphere Perpetual Moon displays the moon phases as they can be seen both from the northern and southern hemispheres respectively, all in a single watch.

A perfect example of Arnold & Son’s technical and artistic excellence, the HM Double Hemisphere Perpetual Moon displays the poetic complication indicating the different phases of moon with rich guilloché dials and two three-dimensional big moons.

The 42 mm case is created in 18-karat red gold and houses the manufacture Arnold & Son mechanical hand-wound movement, the calibre A&S1512. The 27 jewel calibre offers one of the most accurate moon phases on the market, with only one day’s deviation every 122 years – at which point a single push on the corrector will keep it in sync for another 122 years. The calibre is also equipped with a double barrel to yield 90 hours of power reserve.

The exceptional perpetual moon phase indication displayed by the 29 mm moon phase disc, which runs from 10 to 2 and 4 to 8 o’clock on the dial, reveals not one but two of the largest moons on the market – with a diameter of 11.20 mm for the moons alone. While the first aperture displays the moon phase as seen in the northern hemisphere, a mirror image of the moon phase also shows the state of the moon in the southern hemisphere.

Additionally, these large moons are one of the most visually stunning recreations of the moon because they are three-dimensional sculptured moons that were first hand engraved and then duplicated for the series. The two sculptured moons are then inserted into the disc.

From the technical side, in addition to the HM Double Hemisphere Perpetual Moon being so precise, it is also an intriguing complication in that it is not simply a module added to the movement, but, in fact, is fully integrated into the calibre. The watch also has a unique easy-to-set feature thanks to the ingenious addition of a third moon phase indication installed at the back of the movement. This third moon display, visible via a transparent case back, features a graduated dial and a pointer hand that allows for a more exact setting.

The multiple technological advancements in the calibre make this timepiece truly outstanding. To further underscore that, the entire rhodium treated nickel-silver movement features hand finishing indicative of the finest Haute Horlogerie timepieces, including manually chamfered bridges with polished edges, fine circular graining with polished edges and Côtes de Genève rayonnantes, and blued screws. The timepiece naturally features an anti-reflective sapphire crystal and case back to view the meticulous details.

The HM Double Hemisphere Perpetual Moon is created in 18-karat red gold with an incredible blue guilloché dial in a stylized sunray pattern, blue guilloché moon disc with golden stars and two engraved moons.  The timepiece is accented with a hand stitched alligator strap.

Technical details
Model: HM Double Hemisphere Perpetual Moon
Reference:  1GLAR.U03A.C122A, 18-karat red gold case, blue guilloché dial

Calibre:  A&S1512
Manufacture Arnold & Son calibre, hand-wound, big perpetual moons, 27 jewels, diameter 34 mm, thickness
5.35 mm, power reserve 90 h, two barrels, 21’600 vibrations/h
Movement decoration:  nickel-silver movement, rhodium treated with Haute Horlogerie finishing: manually chamfered bridges with polished edges, fine circular graining and Côtes de Genève rayonnantes, blued screws

Translucent blue lacquered guilloché, translucent blue lacquered guilloché moon disc with golden moon and stars; back dial: fine circular graining, rhodium treated, rendition of the 8 phases of the moon

Hours, minutes, two big perpetual moon phase indications on the front, diameter disc: 29 mm, diameter moons: 11.20 mm, third moon phase indication on the back for setting purposes

18-karat red gold, diameter 42 mm, cambered sapphire with antireflective coating on both sides, case back see-through sapphire, water-resistant to 30 m

Hand-stitched black or brown alligator leather


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